Finite element modeling to characterize the stress evolution in asteroid (99942) Apophis during the 2029 Earth encounter

The present study develops an approach combining a dynamics model and a finite element model (FEM) to characterize stress variations in Asteroid (99942) Apophis, a potentially hazardous asteroid (PHA) that approaches ∼6 Earth radii from the geocenter in 2029. Assuming that shape deformation is small, this approach simultaneously simulates the dynamic (rotation and translation) and structural (stress) evolution of an irregularly shaped body with time. We incorporate Apophis’ radar-driven shape model and trajectory to the FEM approach and analyze the stress evolution in this asteroid during the 2029 closest encounter. Considering the rotational uncertainties driven by optical and radar observations in 2012–2013, we investigate how the rotational condition affects the stress variations. The results from 216 rotational cases show that rotation contributes to changing stress variations; however, the predicted stress variations are up to 0.5 Pa, implying that the tidal effect on the structure is minimal. Statistically, the neck regions are more sensitive to stress variations than other areas. Our study suggests that the rotational and shape conditions are key to better constraining Apophis’ geophysical behavior during its 2029 closest encounter.